Sigma 20-40 mm EX DG image quality

[gisle]

I've already have the Sigma 18-50 mm f/3.5-5.6 DC (kit) lens, but wanted someting faster and sharper. Recently, I bought the Sigma 20-40 mm f/2.8 EX DG.

So far, I've been disappointed with the IQ, and today I made some controlled test-shots comparing the 20-40mm DG to the 18-50 DC. All test shots was taken with camera on tripod, using a wired remote. Converted in SPP, no sharpening.

I've put three of the test shots at Flickr (100% crops). The first shows how the lens perform wide open at f/2.6 (f=35 mm), the other two show center and edge frames at f/5.0 and f/16, compared to the 18-50mm DC.

I would appreciate if some here that knows this lens could take a look at my test shots and report if this is the type of IQ I should excpect, or if my sample of the 10-20mm f/2.8 a lemon and should be returned under warranty.

It is still under warranty, but I thought I should get some informed opinions before contacting Sigma.

You'll find my photostream here:
http://flickr.com/photos/gisleh/385431571/in/photostream/

or ...







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• gisle [ http://folk.uio.no/gisle/album/ ]

 

[blazeicehockey]

Does anyone have this lens - looks like a nice focal scope?

I've already have the Sigma 18-50 mm f/3.5-5.6 DC (kit) lens, but
wanted someting faster and sharper. Recently, I bought the Sigma
20-40 mm f/2.8 EX DG.

So far, I've been disappointed with the IQ, and today I made some
controlled test-shots comparing the 20-40mm DG to the 18-50 DC. All
test shots was taken with camera on tripod, using a wired remote.
Converted in SPP, no sharpening.

I've put three of the test shots at Flickr (100% crops). The first
shows how the lens perform wide open at f/2.6 (f=35 mm), the other
two show center and edge frames at f/5.0 and f/16, compared to the
18-50mm DC.

I would appreciate if some here that knows this lens could take a
look at my test shots and report if this is the type of IQ I should
excpect, or if my sample of the 10-20mm f/2.8 a lemon and should be
returned under warranty.

It is still under warranty, but I thought I should get some informed
opinions before contacting Sigma.

You'll find my photostream here:
http://flickr.com/photos/gisleh/385431571/in/photostream/

or ...







--

• gisle [ http://folk.uio.no/gisle/album/ ]

--
Darrin

http://www.flickriver.com/photos/blazeicehockey/

 

[Adam-T]

I have this lens in Pentax fit and optically (this sample at least) is the most impressive wide angle zoom I've seen optically - it eats Sigma's Sad F1.8EX primes (20/24/28) for breakfast for F2.8 performance let alone jokes like the Canon 16-35L Mk1 and rubbish like the Sigma 17-35 F2.8-4 EX - it also beats all the 18, 20, 24 and 28mm primes from Nikon and canon and dare I say it, Nikon's 17-35 F2.8 and 17-55 F2.8 DX for across the frame sharpness end to end with less CA !..

Sooooooooo why isn't it Rated ?? - because every damn one of them I've used in Canon, Nikon, Pentax and Sigma have had serious AF issues .. there's design fault in the FIRMWARE (in P and C at least) where the lens shifts focus depending on where the aperture is set to on the camera - for instance, set the cam to F2.8 and the scale will read infinity - set it to F5.6 or smaller and it'll read CLOSER - the result is that from experience the lens can only EITHER be accurate wideopen OR accurate at F5.6 or smaller (the Firmware in the lens is too clever for its own good), mine rear focusses at F2.8 and front focusses at F5.6 - I'm hoping Sigma Japan can fix it..

I think you'll find that Manually focussed the lens is breathtakingly sharp end to end edge to edge wideopen - if it's not it's a DUD Copy and needs returning..

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Please ignore the Typos, I'm the world's worst Typist